The present invention relates to a surfactant.
Surfactants are generally possessed of a diversity of activities such as emulsifying, dispersing, detergent, wetting, foaming and other activities and as such have been utilized in almost all fields of modern industry such as paper, rubber, plastics, metal, paints, pigments and even civil engineering. Recently, particularly active attempts have been made to utilize surfactants for improving the performance of many end products but several concomitant drawbacks of surfactants have also come to be recognized in the course of such development endeavors.
Taking paints, printing inks, adhesives and pressure-sensitive adhesives as examples, surfactants are indispensable for the manufacture or stabilization of these products or in terms of processability. However, after such products have once been used for coating, printing, adhesion or pressure bonding, the surfactants are no longer necessary. Rather, if they remain in the products, surfactants tend to adversely affect the resistance of the film, print or adhesive layer to water and oil in many instances.
Reduction of the level of addition of surfactants or increase of the molecular weight of surfactants have been the common approaches taken these days to overcome the problems but no satisfactory solutions have been found as yet in terms of product stability and workability.
Meanwhile, as surfactants for use as emulsifiers for emulsion polymerization, anionic surfactants such as sodium dodecylbenzenesulfonate and nonionic surfactants such as polyoxyethylene nonylphenyl ether are known. However, the film of a polymer emulsion prepared using such an emulsifier has the drawbacks of poor resistance to water and poor bond strength because the emulsifier remains in free form in the polymer film.
To obviate these problems, several reactive emulsifiers containing copolymerizable unsaturated groups have been proposed.
For example, anionic reactive surfactants have been disclosed in Japanese Patent Publication No. 46-12472, Japanese Kokai Patent Publication No. 54-144317, Japanese Patent Publication No. 46-34894, Japanese Patent Publication No. 56-29657, Japanese Kokai Patent Publication No. 51-30285, Japanese Patent Publication No. 49-46291, and Japanese Kokai Patent Publication No. 56-127697, while nonionic reactive surfactants have been described in Japanese Kokai Patent Publication No. 56-28208 and No. 50-98484, among others, and emulsion polymerization of various monomers using these emulsifiers has been attempted.
Generally speaking, reactive emulsifiers containing an acryl or methacryl group as the copolymerizable unsaturated group are well copolymerizable with various monomers but are unsatisfactory in terms of the stability of emulsion polymerization reaction, giving rise to gels in the course of polymerization to produce coarse emulsion grains, and/or tend to give an emulsion poor in storage stability.
Reactive emulsifiers containing an allyl group as said copolymerizable unsaturated group have also been described in Japanese Kokai Patent Publication No. 62-100502, No. 62-221431 and No. 63-23725, among others, but these emulsifiers are often poor in copolymerizability with monomers and the polymer films molded from emulsions obtainable with such emulsifiers are not fully satisfactory in water resistance and in bond strength.